Mexico will ask for further information from the U.S. government on its plans to send migrants seeking asylum in the United States to Mexico while their cases are processed, Mexican foreign minister Marcelo Ebrard said on Monday.

Mexico will invest more than $30 billion in its poor southern states over the next five years, the foreign minister said on Monday, boosting the region economically as part of efforts to curb migration.

Central American migrants stuck on the threshold of the United States in Mexico breached the border fence on Monday, risking almost certain detention by U.S. authorities but hoping the illegal entry will allow them to apply for asylum.

Hundreds of Central American migrants in Mexico massed on Thursday around a tense U.S. border crossing, where security measures held up long lines of Mexicans headed to Thanksgiving gatherings on the other side of the frontier.